1. Field of the Invention
The invention relates to a battery, a production method for a battery, and a battery production-purposed mask member. More particularly, the invention relates to a technology of producing a battery terminal structure.
2. Description of Related Art
In a battery having a shape with cornered faces (hereinafter called as a square shape), an exterior houses an electricity-generating element of the battery. Within the exterior there are disposed current-collecting terminal members that extend through a wall of the exterior and protrude out of the exterior hath on a positive electrode terminal side and on a negative electrode terminal side. Inside the exterior, a first end of each current-collecting terminal member is electrically connected to the electricity-generating element, and outside the exterior, a second end of each current-collecting terminal member is electrically connected to a corresponding external terminal member. Therefore, electric power can be given and received between inside and outside the battery.
In some cases, platy connection members are used to electrically connect, outside the exterior, the second ends (outside ends) of the current-collecting terminal members to the external terminal members. There is a known technology of interconnecting the second end of a current-collecting terminal member and a connection member by swaging the second end of the current-collecting terminal member to an insertion hole formed in the connection member (see, for example, Japanese Patent Application Publication No. 2012-028246 (JP 2012-028246 A)).
When the second end of a current-collecting terminal member and a connection member are connected by swaging the second end of the current-collecting terminal member to the connection member as in JP 2012-028246 A, an outer peripheral side end portion of the swaged second end of the current-collecting terminal member, in some cases, is welded to the connection member in order to secure electric conductivity between the current-collecting terminal member and me connection member.
However, if, as shown in FIG. 6A, an imaginary line passing through a weld portion (i.e., portions that are to be welded or that have been welded) W on the outer peripheral side end portion of the second end of the current-collecting terminal member and a center O of the second end of the current-collecting terminal member is more closely leaned to the longitudinal direction of a lid member of the battery than the lateral direction of the lid member of the battery, that is, if, in FIG. 6A, the acute angle α between a line L0 and a center line Lc is relatively small, thermal shrinkage at the time of welding causes tensile stress in the connection member in the longitudinal direction of the Sid member as show by arrows F and F in FIG. 6B. Here, the line L0 connects a weld portion W of the current-collecting terminal member and a center O of the second end of the current-collecting terminal member. The center line Lc extends in the longitudinal direction of the lid member. This causes a force that pivots the connection member in the direction of an arrow R in FIG. 6B, bending the connection member as indicated by a two-dot chain line. If such a bend occurs on the connection member, mere is possibility of occurrence of a problem or inconvenience in which when a bus bar or the like is attached to the external terminal member in a later process, the bus bar or the like cannot be fastened by a nut.